Can all androids video chat with each other? I have the note 9 and my dad has the s7 edge, and it doesn't seem to work? I'm taking about The android video chat that appears when you call someone, not an external chat app?

the short answer is yes all Androids can video chat with each other using an external third-party chat app like Google duo which also works with iPhones.

The long answer is no not necessarily because what you want to do is use the native built-in video chat feature which both phones have to be on T-Mobile and be capable with the feature. This does not work from one carrier to another using the native app feature.

If both phones are on T-Mobile and both phones are T-Mobile branded as in not unlocked from another carrier or from another place of purchase other than T-Mobile then both will have to be capable compatible with vo LTE enabled with proper signal and in good coverage area. I'm not sure why you would not have that capability between two T-Mobile branded devices.

What do you mean by "It doesn't work" specifically? Are you not seeing the option to video call? Are you video calling and it fails, or is the video choppy? No sure if you are interested in a 3rd party app but as snn555 suggested, Google Duo is pretty awesome especially if there are only a couple people you video chat with. It would be pretty easy to get the app installed on each of your devices and you would not have to worry about device compatibility.

So to use T-Mobile Video calling, both devices would need to be a T-Mobile video calling device and have VoLTE enabled. Most phones that are from other carriers may not support T-Mobile VoLTE as they would need to also support WiFi calling and E911 and WiFi calling is not supported on non T-Mobile phones. Your best bet here is going to be using a 3rd party app.